A head mounted display (“HMD”) is a display device worn on or about the head. HMDs usually incorporate some sort of near-to-eye optical system to emit a light image within a few centimeters of the human eye. Single eye displays are referred to as monocular HMDs while dual eye displays are referred to as binocular HMDs. Some HMDs display only a computer generated image (“CGI”), while other types of HMDs are capable of superimposing CGI over a real-world view. This latter type of HMD can serve as the hardware platform for realizing augmented reality. With augmented reality, the viewer's image of the world is augmented with an overlaying CGI, also referred to as a heads-up display (“HUD”).
HMDs have numerous practical and leisure applications. Aerospace applications permit a pilot to see vital flight control information without taking their eye off the flight path. Public safety applications include tactical displays of maps and thermal imaging. Other application fields include video games, transportation, and telecommunications. In the various applications of using HMDs, it is important to maintain the integrity of the CGI that is directed into the user's eye. Consequently, the optics responsible for directing the CGI light to the user's eye must be designed to deliver a quality image to the user. In some contexts, conventional optics for HMDs generate artifacts such as “streaking” in the CGI. “Streaking” may cause the user to perceive an image that includes gaps and/or redundant portions, for example. Therefore, it would be beneficial to have optics that reduce artifacts in the CGI directed to users.